Pseudo-envelope following power management system

Abstract

Embodiments disclosed in the detailed description relate to a pseudo-envelope follower power management system used to manage the power delivered to a linear RF power amplifier.

What is claimed is: 
     
       1. A power management system for an RF power amplifier comprising:
 a parallel amplifier circuit comprising:
 an amplifier in communication with a power amplifier supply voltage; and 
 a voltage offset loop circuit configured to provide a threshold offset current as a feedback signal; and 
 
 a multi-level charge pump buck converter comprising:
 a switcher control circuit configured to receive the feedback signal from the voltage offset loop circuit and output a logic level indication; and 
 a frequency lock loop (FLL) in communication with the switcher control circuit and receiving the logic level indication. 
 
 
     
     
       2. The power management system of  claim 1 , further comprising a coupling circuit coupled to an output of the parallel amplifier circuit, and wherein the feedback signal estimates a magnitude of an offset voltage appearing across the coupling circuit. 
     
     
       3. The power management system of  claim 1 , wherein the voltage offset loop circuit comprises a first subtractor circuit, the first subtractor circuit comprising a voltage offset output, the first subtractor circuit configured to receive the power amplifier supply voltage and an output from the parallel amplifier circuit. 
     
     
       4. The power management system of  claim 3 , wherein the voltage offset loop circuit comprises a second subtractor circuit, the second subtractor circuit comprising an input coupled to the voltage offset output and an offset error output. 
     
     
       5. The power management system of  claim 4 , wherein the voltage offset loop circuit comprises an integrator coupled to the offset error output and wherein the integrator comprises a threshold offset current output. 
     
     
       6. The power management system of  claim 1  wherein as the threshold offset current rises above zero current, an output frequency of the multi-level charge pump buck converter is lowered. 
     
     
       7. The power management system of  claim 6 , further comprising a power inductor coupled to an output of the multi-level charge pump buck converter, wherein as the output frequency decreases, current output from the power inductor decreases. 
     
     
       8. The power management system of  claim 7 , wherein as the current output from the power inductor decreases, an offset voltage within the voltage offset loop circuit decreases. 
     
     
       9. The power management system of  claim 1  wherein as the threshold offset current sinks below zero current, an output frequency of the multi-level charge pump buck converter is increased. 
     
     
       10. The power management system of  claim 9 , further comprising a power inductor coupled to an output of the multi-level charge pump buck converter, wherein as the output frequency increases, current output from the power inductor increases. 
     
     
       11. The power management system of  claim 10 , wherein as the current output from the power inductor increases, an offset voltage within the voltage offset loop circuit increases. 
     
     
       12. A method of controlling a power management system for an RF power amplifier, comprising:
 providing a threshold offset current as a feedback signal from a voltage offset loop circuit; 
 receiving the feedback signal at a switcher control circuit of a multi-level charge pump buck converter; 
 outputting a logic level indication from the switcher control circuit; 
 receiving the logic level indication at a frequency lock loop (FLL). 
 
     
     
       13. The method of  claim 12  further comprising estimating, with the feedback signal, a magnitude of an offset voltage appearing across a coupling circuit. 
     
     
       14. The method of  claim 12 , further comprising generating a threshold offset current output with an integrator in the voltage offset loop circuit. 
     
     
       15. The method of  claim 12 , further comprising lowering an output frequency of the multi-level charge pump buck converter as the threshold offset current rises above zero current. 
     
     
       16. The method of  claim 12 , further comprising increasing an output frequency of the multi-level charge pump buck converter as the threshold offset current sinks below zero current.